Korolev crater is 82 kilometres across and found in the northern lowlands of Mars, just south of a large patch of dune-filled terrain that encircles part of the planet’s northern polar cap (known as Olympia Undae). It is an especially well-preserved example of a martian crater and is filled not by snow but ice, with its centre hosting a mound of water ice some 1.8 kilometres thick all year round.

This ever-icy presence is due to an interesting phenomenon known as a ‘cold trap’, which occurs as the name suggests. The crater’s floor is deep, lying some two kilometres vertically beneath its rim.

The very deepest parts of Korolev crater, those containing ice, act as a natural cold trap: the air moving over the deposit of ice cools down and sinks, creating a layer of cold air that sits directly above the ice itself.

Behaving as a shield, this layer helps the ice remain stable and stops it from heating up and disappearing. Air is a poor conductor of heat, exacerbating this effect and keeping Korolev crater permanently icy.

The crater is named after chief rocket engineer and spacecraft designer Sergei Korolev, dubbed the father of Soviet space technology.

Korolev worked on a number of well-known missions including the Sputnik program – the first artificial satellites ever sent into orbit around the Earth, in 1957 and the years following, the Vostok and Vokshod programs of human space exploration (Vostok being the spacecraft that carried the first ever human, Yuri Gagarin, into space in 1961) as well as the first interplanetary missions to the Moon, Mars, and Venus. He also worked on a number of rockets that were the precursors to the successful Soyuz launcher – still the workhorses of the Russian space programme, and used for both crewed and robotic flights.

You beat me to it, sir!I was just dropping in to see if this had been discussed already after getting sent a link to a BBC article (of all things) with an artists impression masquerading as a satellite image (ah - that's more like the BBC I have come to know)asking me if I had come across this yet - said I hadn't but would come have a look see.

The more things change, the more they stay the same though but extremely interesting.

You will never get a man to understand something his salary depends on him not understanding.